I am sorry, but having someone's IP address (which is what RIAA uses) associated with a supposedly illegal Internet activity is not sufficient to call it prima facie.

I'm sorry, but I don't understand you. An IP address allows the identity of a specific computer to be determined, does it not? I know that it can refer to different computers at different times, but an ISP can determine which customer that IP address was allocated to at a specific time. In what way does this not constitute evidence, in your view?